Epiphora describes an overflow of tears caused by imperfect drainage of the tear-conducting passages. Epiphora is a common ophthalmic problem, accounting for 3% of ambulatory clinic visits. When tear shedding is extreme, it causes considerable annoyance for patients by degrading visual acuity. The cause of epiphora is usually benign; however, in some cases, malignant nasolacrimal duct obstruction occurs. Current office-based methods for assessing nasolacrimal duct obstruction provide only tactile feedback (i.e., a qualitative measure) for physicians to assess the patency of the nasolacrimal drainage system. Such methods are subjective and prone to overestimation and/or underestimation of lacrimal drainage pressure.